U.S. patent number 11,111,440 [Application Number 17/188,836] was granted by the patent office on 2021-09-07 for apparatus, system, and method for shale pyrolysis.
This patent grant is currently assigned to PYRO DYNAMICS, LLC. The grantee listed for this patent is PYRO DYNAMICS LLC. Invention is credited to Gary G. Otterstrom.
United States Patent |
11,111,440 |
Otterstrom |
September 7, 2021 |
Apparatus, system, and method for shale pyrolysis
Abstract
Apparatuses, systems, and methods are disclosed for shale
pyrolysis. A retort may include a first side and a second side
opposite the first side, where the first side and the second side
include descending angled surfaces at alternating angles to produce
zig-zag motion of shale descending through the retort. Steam
distributors may be coupled to the first side, with collectors
coupled to the second side, to produce crossflow of steam and heat
across the descending shale. A steam temperature control subsystem
may be coupled to the steam distributors and may deliver
higher-temperature steam to an upper portion of the retort and
lower-temperature steam to a lower portion of the retort.
Inventors: |
Otterstrom; Gary G. (Lindon,
UT) |
Applicant: |
Name |
City |
State |
Country |
Type |
PYRO DYNAMICS LLC |
Pleasant Grove |
UT |
US |
|
|
Assignee: |
PYRO DYNAMICS, LLC (Lindon,
UT)
|
Family
ID: |
1000005788147 |
Appl.
No.: |
17/188,836 |
Filed: |
March 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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62982636 |
Feb 27, 2020 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10B
53/06 (20130101); C10B 1/08 (20130101); C10B
49/06 (20130101); C10B 1/04 (20130101); C10B
1/06 (20130101); C10B 49/04 (20130101) |
Current International
Class: |
C10B
49/04 (20060101); C10B 1/08 (20060101); C10B
53/06 (20060101); C10B 49/06 (20060101); C10B
1/04 (20060101); C10B 1/06 (20060101) |
Field of
Search: |
;202/221 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
PCT Application No. PCT/US2018/048614 filed Aug. 29, 2018, Written
Opinion of the International Searching Authority dated Feb. 7,
2019. cited by applicant .
PCT/US2021/020338 filed Mar. 1, 2021, "Written Opinion of the
International Searching Authority", dated May 27, 2021, pp. 1-8.
cited by applicant.
|
Primary Examiner: Pilcher; Jonathan Luke
Attorney, Agent or Firm: Kunzler Bean & Adamson Needham;
Bruce R.
Parent Case Text
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Patent
Application No. 62/982,636 entitled "APPARATUS, SYSTEM, AND METHOD
FOR SHALE PYROLYSIS" and filed on Feb. 27, 2020 for Gary G.
Otterstrom, which is incorporated herein by reference.
Claims
What is claimed is:
1. A shale pyrolysis system comprising: a retort comprising a first
side and a second side, the second side opposite the first side,
the first side and the second side comprising descending angled
surfaces at alternating angles to produce zig-zag motion of shale
descending through the retort; steam distributors coupled to the
first side and collectors coupled to the second side to produce
crossflow of steam and heat across the descending shale from the
first side to the second side; and a steam temperature control
subsystem coupled to the steam distributors and configured to
deliver higher-temperature steam to an upper portion of the retort
and lower-temperature steam to a lower portion of the retort.
2. The system of claim 1, wherein the steam temperature control
subsystem comprises one or more heaters for increasing steam
temperature, and a plurality of steam/water mixers for reducing
steam temperature to a plurality of different temperatures for
delivery to different portions of the retort.
3. The system of claim 2, wherein the plurality of steam/water
mixers are configured to produce steam above 600.degree. F. for
distribution to a preheat section of the retort, steam above
750.degree. F. for distribution to the upper portion of the retort,
and steam below 300.degree. F. for distribution to the lower
portion of the retort.
4. The system of claim 1, wherein the retort comprises a preheat
section for receiving and preheating shale entering the top of the
retort, the preheat section comprising a plurality of preheat steam
distributors disposed between the first side and the second
side.
5. The system of claim 4, wherein the preheat steam distributors
comprise hollow vertical rods with side ports, the hollow vertical
rods extending downward from a grate with hollow members for
receiving steam and distributing steam to the hollow vertical
rods.
6. The system of claim 1, further comprising a shale combustion
subsystem, the shale combustion subsystem comprising: one or more
combustion chambers for combustion of pyrolyzed shale received from
the retort; and one or more heat exchangers for superheating steam
for the steam temperature control subsystem, using heat from the
combustion of the pyrolyzed shale.
7. The system of claim 6, wherein the shale combustion subsystem
further comprises one or more boilers for producing the steam.
8. The system of claim 7, wherein the one or more boilers are
configured to heat pressurized water and produce steam at one or
more pressure release valves, and wherein the shale combustion
subsystem further comprises a pump for providing pressurized water
to the boilers.
9. The system of claim 7, wherein the one or more heat exchangers
for superheating steam comprise vertical compartments for ascending
steam to be heated by descending shale particles and combustion
gases, and wherein the one or more boilers comprise horizontal
compartments for water to be heated by gases from which solids have
been removed.
10. The system of claim 9, wherein the shale combustion subsystem
further comprises one or more cyclonic separators disposed between
the one or more heat exchangers for superheating steam and the one
or more boilers, for removing the solids from the gases.
11. The system of claim 7, further comprising one or more filter
houses comprising iron-zinc filters for removing hydrogen sulfide
from a horizontal flow of combustion gases, and a vertical flow of
water for removing carbon dioxide from the combustion gases.
12. The system of claim 1, further comprising a distillation
subsystem, the distillation subsystem comprising a plurality of
liquid/gas separation vessels that receive gases from the retort,
and a plurality of organic Rankine cycle (ORC) generators
corresponding to the separation vessels, wherein: the ORC
generators are coupled to and powered by heat exchangers of the
separation vessels; the ORC generators comprise different working
fluids to produce different condensation temperatures for gases in
different separation vessels; and the separation vessels are
coupled in a chain such that gases exiting earlier separation
vessels in the chain are received by later separation vessels in
the chain.
13. The system of claim 12, wherein the separation vessels comprise
four separation vessels for condensing hydrocarbons at different
condensation temperatures, and a fifth separation vessel for
condensing water.
14. A method of shale pyrolysis, comprising: providing a retort
comprising a first side and a second side, the second side opposite
the first side, the first side and the second side comprising
descending angled surfaces at alternating angles to produce zig-zag
motion of shale descending through the retort; providing steam
distributors coupled to the first side and collectors coupled to
the second side to produce crossflow of steam and heat across the
descending shale from the first side to the second side; providing
a steam temperature control subsystem coupled to the steam
distributors and configured to deliver higher-temperature steam to
an upper portion of the retort and lower-temperature steam to a
lower portion of the retort; filling the retort with shale; moving
shale through the retort by continuously removing shale at the
bottom of the retort and adding shale at the top; pyrolyzing the
shale by using the steam temperature control subsystem and the
steam distributors to deliver the higher-temperature steam to the
upper portion of the retort and the lower-temperature steam to the
lower portion of the retort; and removing shale pyrolysis gases and
the steam via the collectors.
15. The method of claim 14, further comprising: providing a preheat
section of the retort, comprising a plurality of preheat steam
distributors disposed between the first side and the second side;
and delivering steam to the preheat section to preheat shale
entering the top of the retort.
16. The method of claim 14, further comprising combusting pyrolyzed
shale received from the retort to produce and superheat steam for
the steam temperature control subsystem.
17. The method of claim 14, further comprising: providing a
plurality of liquid/gas separation vessels coupled in a chain such
that gases exiting earlier separation vessels in the chain are
received by later separation vessels in the chain; and directing
gases from the retort through the plurality of separation vessels
to remove condensable hydrocarbons and water from the gases.
18. The method of claim 17 further comprising: providing a
plurality of organic Rankine cycle (ORC) generators coupled to and
powered by heat exchangers of the separation vessels, wherein the
ORC generators comprise different working fluids to produce
different condensation temperatures for gases in different
separation vessels; removing different distillation cuts of
condensed hydrocarbons, corresponding to the different condensation
temperatures, from the separation vessels; and using the ORC
generators to produce electricity using heat from condensing the
hydrocarbons.
Description
FIELD
The subject matter disclosed herein relates to oil and gas
production and more particularly relates to shale pyrolysis.
BACKGROUND
Oil and gas may be produced from oil shale by a process of
pyrolysis. At suitably high temperatures, kerogen in the shale
thermally decomposes, releasing gases and vapors that may be
recovered as shale gas and shale oil. Although oil shale is
abundant, shale oil production costs have, at times, been
uncompetitive with economical sources of conventional crude oil.
Shale oil production costs may include the cost of retorting
equipment with limited throughput, pre-production costs (e.g., to
meet shale particle size limits), energy costs, water costs, and
the like.
SUMMARY
Apparatuses, systems, and methods are disclosed for shale
pyrolysis. A system, in one embodiment, includes a retort, steam
distributors and collectors, and a steam temperature control
subsystem. A retort, in one embodiment, includes a first side and a
second side opposite the first side. In a further embodiment, the
first side and the second side include descending angled surfaces
at alternating angles to produce zig-zag motion of shale descending
through the retort. In one embodiment, steam distributors are
coupled to the first side and collectors are coupled to the second
side, to produce crossflow of steam and heat across the descending
shale from the first side to the second side. A steam temperature
control subsystem, in one embodiment, is coupled to the steam
distributors and configured to deliver higher-temperature steam to
an upper portion of the retort and lower-temperature steam to a
lower portion of the retort.
An apparatus for shale pyrolysis, in one embodiment, includes a
retort, and hot gas distributors and collectors. A retort, in one
embodiment, includes a first side and a second side opposite the
first side. In further embodiments, the first side and the second
side include descending angled surfaces at alternating angles to
produce zig-zag motion of shale descending through the retort. Hot
gas distributors, in one embodiment, are coupled to the first side,
and collectors are coupled to the second side, to produce crossflow
of a hot gas across the descending shale from the first side to the
second side.
A method for shale pyrolysis, in one embodiment, includes providing
a retort including a first side and a second side opposite the
first side. The first side and the second side may include
descending angled surfaces at alternating angles to produce zig-zag
motion of shale descending through the retort. In a further
embodiment, the method includes providing steam distributors
coupled to the first side and collectors coupled to the second side
to produce crossflow of steam and heat across the descending shale
from the first side to the second side. In a further embodiment,
the method includes providing a steam temperature control subsystem
coupled to the steam distributors and configured to deliver
higher-temperature steam to an upper portion of the retort and
lower-temperature steam to a lower portion of the retort. In a
further embodiment, the method includes filling the retort with
shale, and moving shale through the retort by continuously removing
shale at the bottom of the retort and adding shale at the top. In a
further embodiment, the method includes pyrolyzing the shale by
using the steam temperature control subsystem and the steam
distributors to deliver the higher-temperature steam to the upper
portion of the retort and the lower-temperature steam to the lower
portion of the retort. In a further embodiment, the method includes
removing shale pyrolysis gases and the steam via the
collectors.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the advantages of the invention will be readily
understood, a more particular description of the invention briefly
described above will be rendered by reference to specific
embodiments that are illustrated in the appended drawings.
Understanding that these drawings depict only typical embodiments
of the invention and are not therefore to be considered to be
limiting of its scope, the invention will be described and
explained with additional specificity and detail through the use of
the accompanying drawings, in which:
FIG. 1 is a perspective view illustrating one embodiment of a shale
pyrolysis system;
FIG. 2A is a partial view of the shale pyrolysis system of FIG.
1;
FIG. 2B is a partial view of the shale pyrolysis system of FIG.
1;
FIG. 2C is a partial view of the shale pyrolysis system of FIG.
1;
FIG. 3 is a diagram illustrating one embodiment of a steam
temperature control subsystem;
FIG. 4 is a diagram illustrating one embodiment of a retort;
FIG. 5 is a perspective view illustrating one embodiment of a
preheat section for a retort;
FIG. 6 is a perspective view illustrating a portion of a retort
below a preheat section, in one embodiment;
FIG. 7 is a perspective view illustrating a steam distributor and a
collector for a retort, in one embodiment;
FIG. 8 is a diagram illustrating one embodiment of a distillation
subsystem;
FIG. 9 is a diagram illustrating one embodiment of a shale
combustion subsystem;
FIG. 10 is a perspective view illustrating embodiments of
components of a shale combustion subsystem; and
FIG. 11 is a perspective view illustrating one embodiment of a
filter house.
DETAILED DESCRIPTION
Reference throughout this specification to "one embodiment," "an
embodiment," or similar language means that a particular feature,
structure, or characteristic described in connection with the
embodiment is included in at least one embodiment. Thus,
appearances of the phrases "in one embodiment," "in an embodiment,"
and similar language throughout this specification may, but do not
necessarily, all refer to the same embodiment, but mean "one or
more but not all embodiments" unless expressly specified otherwise.
The terms "including," "comprising," "having," and variations
thereof mean "including but not limited to" unless expressly
specified otherwise. An enumerated listing of items does not imply
that any or all of the items are mutually exclusive and/or mutually
inclusive, unless expressly specified otherwise. The terms "a,"
"an," and "the" also refer to "one or more" unless expressly
specified otherwise.
Furthermore, the described features, structures, or characteristics
of the invention may be combined in any suitable manner in one or
more embodiments. In the following description, numerous specific
details are included to provide a thorough understanding of
embodiments of the invention. One skilled in the relevant art will
recognize, however, that the invention may be practiced without one
or more of the specific details, or with other methods, components,
materials, and so forth. In other instances, well-known structures,
materials, or operations are not shown or described in detail to
avoid obscuring aspects of the invention.
The schematic flow chart diagrams included herein are generally set
forth as logical flow chart diagrams. As such, the depicted order
and labeled steps are indicative of one embodiment of the presented
method. Other steps and methods may be conceived that are
equivalent in function, logic, or effect to one or more steps, or
portions thereof, of the illustrated method. Additionally, the
format and symbols employed are provided to explain the logical
steps of the method and are understood not to limit the scope of
the method. Although various arrow types and line types may be
employed in the flow chart diagrams, they are understood not to
limit the scope of the corresponding method. Indeed, some arrows or
other connectors may be used to indicate only the logical flow of
the method. For instance, an arrow may indicate a waiting or
monitoring period of unspecified duration between enumerated steps
of the depicted method. Additionally, the order in which a
particular method occurs may or may not strictly adhere to the
order of the corresponding steps shown.
As used herein, a list with a conjunction of "and/or" includes any
single item in the list or a combination of items in the list. For
example, a list of A, B and/or C includes only A, only B, only C, a
combination of A and B, a combination of B and C, a combination of
A and C or a combination of A, B and C. As used herein, a list
using the terminology "one or more of" includes any single item in
the list or a combination of items in the list. For example, one or
more of A, B and C includes only A, only B, only C, a combination
of A and B, a combination of B and C, a combination of A and C or a
combination of A, B and C. As used herein, a list using the
terminology "one of" includes one and only one of any single item
in the list. For example, "one of A, B and C" includes only A, only
B or only C and excludes combinations of A, B and C. As used
herein, "a member selected from the group consisting of A, B, and
C," includes one and only one of A, B, or C, and excludes
combinations of A, B, and C." As used herein, "a member selected
from the group consisting of A, B, and C and combinations thereof"
includes only A, only B, only C, a combination of A and B, a
combination of B and C, a combination of A and C or a combination
of A, B and C.
Aspects, components, or subsystems of one embodiment of a shale
pyrolysis system are described herein. The described aspects,
components, or subsystems may be used in combination as described
herein, or may be used individually, or in subcombinations in other
embodiments of shale pyrolysis systems, alongside other shale
pyrolysis components or subsystems. For example, a retort and a
distillation subsystem are described herein, but the retort may be
used with a distillation column other than the described
distillation subsystem, or the distillation subsystem may be used
with a retort other than the described retort.
Apparatuses, systems, and methods are disclosed for shale
pyrolysis. A system, in one embodiment, includes a retort, steam
distributors and collectors, and a steam temperature control
subsystem. A retort, in one embodiment, includes a first side and a
second side opposite the first side. In a further embodiment, the
first side and the second side include descending angled surfaces
at alternating angles to produce zig-zag motion of shale descending
through the retort. In one embodiment, steam distributors are
coupled to the first side and collectors are coupled to the second
side, to produce crossflow of steam and heat across the descending
shale from the first side to the second side. A steam temperature
control subsystem, in one embodiment, is coupled to the steam
distributors and configured to deliver higher-temperature steam to
an upper portion of the retort and lower-temperature steam to a
lower portion of the retort.
In some embodiments, the steam temperature control subsystem
includes one or more heaters for increasing steam temperature, and
a plurality of steam/water mixers for reducing steam temperature to
a plurality of different temperatures for delivery to different
portions of the retort. In some embodiments, the plurality of
steam/water mixers are configured to produce steam above
600.degree. F. for distribution to a preheat section of the retort,
steam above 750.degree. F. for distribution to the upper portion of
the retort, and steam below 300.degree. F. for distribution to the
lower portion of the retort.
The retort, in some embodiments, includes a preheat section for
receiving and preheating shale entering the top of the retort. In
some embodiments, the preheat section includes a plurality of
preheat steam distributors disposed between the first side and the
second side. In some embodiments, the preheat steam distributors
include hollow vertical rods with side ports. The hollow vertical
rods may extend downward from a grate with hollow members for
receiving steam and distributing steam to the hollow vertical
rods.
In some embodiments, a system includes a shale combustion
subsystem, including one or more combustion chambers for combustion
of pyrolyzed shale received from the retort, and one or more heat
exchangers for superheating steam for the steam temperature control
subsystem, using heat from the combustion of the pyrolyzed shale.
In some embodiments, the shale combustion subsystem further
includes one or more boilers for producing the steam. The one or
more boilers may be configured to heat pressurized water and
produce steam at one or more pressure release valves, and the shale
combustion subsystem may include a pump for providing pressurized
water to the boilers.
In some embodiments, one or more heat exchangers for superheating
steam include vertical compartments for ascending steam to be
heated by descending shale particles and combustion gases. In
further embodiments, one or more boilers may include horizontal
compartments for water to be heated by gases from which solids have
been removed. In some embodiments, the shale combustion subsystem
further includes one or more cyclonic separators disposed between
the one or more heat exchangers for superheating steam and the one
or more boilers, for removing the solids from the gases. In some
embodiments, a system may include one or more filter houses, which
may include iron-zinc filters for removing hydrogen sulfide from a
horizontal flow of combustion gases, and a vertical flow of water
for removing carbon dioxide from the combustion gases.
In some embodiments, a system may include a distillation subsystem,
including a plurality of liquid/gas separation vessels that receive
gases from the retort, and a plurality of organic Rankine cycle
(ORC) generators corresponding to the separation vessels. In some
embodiments, the ORC generators are coupled to and powered by heat
exchangers of the separation vessels, and include different working
fluids to produce different condensation temperatures for gases in
different separation vessels. The separation vessels may be coupled
in a chain so that gases exiting earlier separation vessels in the
chain are received by later separation vessels in the chain. In
some embodiments, the separation vessels may include four
separation vessels for condensing hydrocarbons at different
condensation temperatures, and a fifth separation vessel for
condensing water.
An apparatus for shale pyrolysis, in one embodiment, includes a
retort, and hot gas distributors and collectors. A retort, in one
embodiment, includes a first side and a second side opposite the
first side. In further embodiments, the first side and the second
side include descending angled surfaces at alternating angles to
produce zig-zag motion of shale descending through the retort. Hot
gas distributors, in one embodiment, are coupled to the first side,
and collectors are coupled to the second side, to produce crossflow
of a hot gas across the descending shale from the first side to the
second side.
In some embodiments, the hot gas is steam. In further embodiments,
a steam temperature control subsystem may be coupled to the hot gas
distributors and configured to deliver higher-temperature steam to
an upper portion of the retort and lower-temperature steam to a
lower portion of the retort.
A method for shale pyrolysis, in one embodiment, includes providing
a retort including a first side and a second side opposite the
first side. The first side and the second side may include
descending angled surfaces at alternating angles to produce zig-zag
motion of shale descending through the retort. In a further
embodiment, the method includes providing steam distributors
coupled to the first side and collectors coupled to the second side
to produce crossflow of steam and heat across the descending shale
from the first side to the second side. In a further embodiment,
the method includes providing a steam temperature control subsystem
coupled to the steam distributors and configured to deliver
higher-temperature steam to an upper portion of the retort and
lower-temperature steam to a lower portion of the retort. In a
further embodiment, the method includes filling the retort with
shale, and moving shale through the retort by continuously removing
shale at the bottom of the retort and adding shale at the top. In a
further embodiment, the method includes pyrolyzing the shale by
using the steam temperature control subsystem and the steam
distributors to deliver the higher-temperature steam to the upper
portion of the retort and the lower-temperature steam to the lower
portion of the retort. In a further embodiment, the method includes
removing shale pyrolysis gases and the steam via the
collectors.
In some embodiments, a method includes providing a preheat section
of the retort, including a plurality of preheat steam distributors
disposed between the first side and the second side. In further
embodiments, a method includes delivering steam to the preheat
section to preheat shale entering the top of the retort. In some
embodiments, a method includes combusting pyrolyzed shale received
from the retort to produce and superheat steam for the steam
temperature control subsystem.
In some embodiments, a method includes providing a plurality of
liquid/gas separation vessels coupled in a chain so that gases
exiting earlier separation vessels in the chain are received by
later separation vessels in the chain. In further embodiments, a
method includes directing gases from the retort through the
plurality of separation vessels to remove condensable hydrocarbons
and water from the gases. In some embodiments, a method includes
providing a plurality of organic Rankine cycle (ORC) generators
coupled to and powered by heat exchangers of the separation
vessels, where the ORC generators include different working fluids
to produce different condensation temperatures for gases in
different separation vessels. In further embodiments, a method
includes removing different distillation cuts of condensed
hydrocarbons, corresponding to the different condensation
temperatures, from the separation vessels, and using the ORC
generators to produce electricity using heat from condensing the
hydrocarbons.
FIG. 1 is a perspective view illustrating one embodiment of a shale
pyrolysis system 100. Partial views of the shale pyrolysis system
100 are depicted in FIGS. 2A, 2B, and 2C, while FIG. 1 is a smaller
scale view showing the whole formed by the partial views, and
indicating the positions of the partial views relative to the
whole. Dashed lines in FIG. 1 indicate the edges of the partial
views of FIGS. 2A, 2B, and 2C.
Referring to FIG. 2A, the depicted embodiment of a shale pyrolysis
system 100 includes horizontal conveyors 202, 208, a shale
combustion subsystem 204, a vertical conveyor 206, a pump 210,
feedwater tanks 212, a sulfuric acid plant 214, a sulfuric acid
storage tank 216, filter houses 218, and algae ponds 220. Referring
to FIG. 2B, the depicted embodiment of a shale pyrolysis system 100
further includes hoppers 232, a retort 234, a steam temperature
control subsystem 236, a vertical conveyor 238, a distillation
subsystem 240, and a horizontal conveyor 242. Referring to FIG. 2C,
the depicted embodiment of a shale pyrolysis system 100 includes
liquid storage tanks 252 and gas storage tanks 254. Operation of
the system 100 is first briefly described below with reference to
FIGS. 2A, 2B, and 2C as a whole, and then individual components are
described in further detail below with reference to subsequent
Figures.
In the depicted embodiment, a horizontal conveyor 202 and a
vertical conveyor 238 convey shale to one or more hoppers 232 above
a retort 234. In general, in various embodiments, shale is heated
in a retort 234 where pyrolysis occurs, releasing gases from
thermal decomposition of kerogen in the shale. The gases include
hydrocarbons which may be separated into different distillate cuts
or fractions by a distillation subsystem 240. The gases may also
include steam, which may similarly be condensed by the distillation
subsystem 240. Liquid and gaseous products of the distillation
subsystem 240 may be stored in liquid storage tanks 252 and gas
storage tanks 254, respectively. Liquid storage tanks 252 store oil
fractions produced by the distillation subsystem 240, while gas
storage tanks 254 store non-condensed gases such as hydrogen,
carbon dioxide, hydrogen sulfide and lighter hydrocarbons (e.g.,
methane through hexane).
In the depicted embodiment, the retort 234 includes opposite sides
(to the left and to the right in FIG. 2B) with descending angled
surfaces at alternating angles to produce zig-zag motion of shale
descending through the retort 234. Thus, the retort 234 in the
depicted embodiment is itself zig-zag shaped. In the depicted
embodiment, steam distributors are coupled to a first side of the
retort 234 (to the left in FIG. 2B), and collectors are coupled to
a second side opposite the first side (to the right in FIG. 2B), to
produce a crossflow of steam and heat across the descending shale
from the first side to the second side. In the depicted embodiment,
the steam temperature control subsystem 236 is coupled to the steam
distributors at the left of the retort 234, and is configured to
deliver higher-temperature steam to an upper portion of the retort
234 and lower-temperature steam to a lower portion of the retort
234. The flow of steam across the retort 234 heats and pyrolyzes
the shale, so that steam and pyrolysis gases are removed from the
retort 234 at the collectors. In various embodiments, a retort 234
as described herein may be capable of pyrolyzing a variety of types
of shale with different minerology and different kerogen
content.
In the depicted embodiment, the retort 234 is filled with shale,
which is moved through the retort 234 from top to bottom, by
removing shale at the bottom of the retort 234 and adding shale at
the top. For example, shale may be moved from hoppers 232 into the
top of the retort 234 by augers, and may similarly be moved from
the bottom of the retort 234 to a horizontal conveyor 242 by
augers. The pyrolyzed shale removed from the retort 234 may include
combustible material, such as various carbon compounds that were
not vaporized in the retort 234 during pyrolysis. In the depicted
embodiment, the horizontal conveyor 242 and the vertical conveyor
206 convey the pyrolyzed shale to a shale combustion subsystem 204,
where the shale is combusted.
(Shale may also include minerals that are not broken down by
pyrolysis or consumed by combustion. Terms such as "shale
pyrolysis" and "shale combustion" should be understood to refer to
processes that affect portions of the shale, such as kerogen
decomposing in the process of pyrolysis, and carbon solids reacting
with oxygen in the process of combustion. Such terms do not imply
that the entirety of the shale is either pyrolyzed or
combusted.)
In the depicted embodiment, a pump 210 pumps water from feedwater
tanks 212 into the shale combustion subsystem 204, which uses heat
from combustion of the pyrolyzed shale to boil the water (producing
steam), and to superheat the resulting steam. Boiling water and
superheating the steam produces pressure to move the steam from the
shale combustion subsystem 204 to the steam temperature control
subsystem 236. The combusted shale cooled by heat transfer to the
water/steam is removed from the system 100 by horizontal conveyor
208. Gases from shale combustion, also cooled by heat transfer to
the water/steam are processed through filter houses 218 to remove
hydrogen sulfide and carbon dioxide. The hydrogen sulfide may be
converted to sulfuric acid at a sulfuric acid plant 214, and stored
in a sulfuric acid storage tank 216. Carbon dioxide may be
dissolved into water, and the resulting carbon enriched water may
be provided to one or more algae ponds 220. Algae in ponds 220 may
process carbon dioxide by photosynthesis to produce algae oil.
Thus, in various embodiments, outputs of the system 100 may include
hydrocarbons from pyrolysis, sulfuric acid, and/or algae oil.
Various steps or components described herein as interrelated can be
run semi-independently for a period of time (e.g., the system 100
as a whole may continue operating if an individual component or
subsystem is offline for maintenance). For example, the steam
temperature control subsystem 236 may temper superheated steam from
the shale combustion subsystem 204, or may produce steam or add
heat to steam if the shale combustion subsystem 204 is not
producing steam at a desired temperature. Shale in the retort 234
may have a large thermal mass, allowing some extra heat to be added
to or removed from the retort as needed. Electrical generators in
the distillation subsystem 240 may be operated across a wide
temperature range without needing extensive human supervision for
temperature changes. Water may be buffered in the feedwater tanks
212 allowing steam to be produced as needed. Thus, various
subsystems or components that depend on each other include buffers
for energy or material, allowing the system 100 as a whole to be
started up, maintained, or operated across a variety of working
conditions without requiring a large degree of coordination between
the components and subsystems.
FIG. 3 is a diagram illustrating one embodiment of a steam
temperature control subsystem 236, as described above. In the
depicted embodiment, the steam temperature control subsystem 236
includes heaters 302, 304 and one or more steam/water mixers 306,
which are described below.
Lines, pipes or other connectors between components or subsystems
in the Figures are intended, as in an electrical schematic diagram,
to indicate how components or subsystems are coupled together and
are not intended to imply exact spatial relationships between
components. For example, the vertical and/or horizontal positions
of heaters 302, 304 and steam/water mixers 306 in a system 100 may
or may not be as depicted in FIG. 3, but the flow of steam between
the components is illustrated by pipes. In the depicted embodiment,
the steam temperature control subsystem 236 receives steam from the
shale combustion subsystem from the pipe depicted entering the left
of FIG. 3, and delivers steam to steam distributors at various
portions of the retort 234 via the pipes depicted exiting the right
of FIG. 3.
In general, in various embodiments, a steam temperature control
subsystem 236 is coupled to steam distributors at the retort 234,
and is configured to deliver higher-temperature steam to an upper
portion of the retort 234 and lower-temperature steam to a lower
portion of the retort 234. With crossflow of steam across the
retort 234 from a first side to a second side, delivering higher
temperature steam to the upper portion of the retort 234 heats
shale near the first side to a hot enough temperature for pyrolysis
in the upper portion. Then, as the shale descends through the
retort 234, delivering lower temperature steam to the lower portion
of the retort 234 cools the already pyrolyzed shale near the first
side and drives a zone of higher temperature towards the second
side of the retort 234 to pyrolyze shale in the interior of the
retort 234 and at the second side. This process is described in
further detail below with reference to FIG. 4.
In some embodiments, a steam temperature control subsystem 236
includes one or more heaters 302, 304 for increasing steam
temperature. In the depicted embodiment, the steam temperature
control subsystem 236 includes two heaters 302, 304. In another
embodiment, a steam temperature control subsystem 236 may include
more or fewer heaters. In the depicted embodiment, heater 302 is a
combustion heater (e.g., an oxy-fuel burner or an air-fuel burner)
that burns fuel to increase the temperature of the steam received
from the shale combustion subsystem 204. As depicted in FIG. 3, a
heater 302 may be disposed in or preceded by a liquid/gas separator
to remove any condensate from the incoming steam. In the depicted
embodiment, heater 304 is an electric heater that uses one or more
resistive heating elements (such as CALROD.RTM. heating elements)
to increase the temperature of the steam. Various other or further
types of heaters may similarly be used to increase steam
temperature in a steam temperature control subsystem 236.
At times, steam received by the steam temperature control subsystem
236 from the shale combustion subsystem 204 may already be at or
above the highest temperature that the steam temperature control
subsystem 236 provides to the retort 234, in which case heaters
302, 304 may not be used. However, at other times, steam may not be
available from the shale combustion subsystem 204 (e.g., at plant
startup), or may be at a lower temperature than desired. Using one
or more heaters 302, 304 provides a buffer between the shale
combustion subsystem 204 and the retort 234 for reheating or
producing steam.
In the depicted embodiment, the steam temperature control subsystem
236 includes a plurality of steam/water mixers 306 for reducing
steam temperature to a plurality of different temperatures for
delivery to different portions of the retort 234. Steam/water
mixers 306 are depicted collectively as a black box in FIG. 3, but
may in reality be disposed near each other or at spatially distant
locations in different steam lines. In various embodiments,
steam/water mixers 306 may be commercially available attemperators,
or the like, which reduce steam temperature by mixing the steam
with water. Thus, the steam temperature control subsystem 236 may
output steam at a variety of temperatures by heating steam to a
high temperature, splitting the heated steam into different output
lines, and reducing the temperature of the steam in one or more of
the output lines. The output lines thus convey steam at different
temperatures to the retort 234.
FIG. 4 is a diagram illustrating one embodiment of a retort 234,
with associated components for a shale pyrolysis system 100 as
described above. The retort 234 and certain other components are
shown in cross section, in a side view, to illustrate internal
components. Certain lines inside the retort 234 are illustrations
of shale flow or heat flow through the retort 234, and not of the
physical structure of the retort 234. As in FIG. 3, lines or other
connectors between components or subsystems indicate the flow of
steam or other gases between components, as in an electrical
schematic diagram, to indicate how components or subsystems are
coupled together and are not intended to imply exact spatial
relationships between components. Additionally, various components
depicted in the Figures may be omitted in some embodiments of a
system 100, and/or various components omitted from the Figures may
be included in some embodiments of a system 100. For example,
although FIG. 3 depicts nine angled sections of a retort 234, a
retort 234 in another embodiment may have more or fewer than nine
sections.
Shale is loaded into the retort 234 at or near the top, is
pyrolyzed as it descends through the retort 234, and is removed
from the bottom of the retort 234. The retort 234 includes a first
side 450 (depicted to the left in FIG. 4), and a second side 460
(depicted to the right in FIG. 4) opposite the first side 450. In
the depicted embodiment, the first and second sides 450, 460
include descending angled surfaces at alternating angles to produce
zig-zag motion of shale descending through the retort 234. The
first and second sides 450, 460, in the depicted embodiment, both
have zig-zag shapes produced by the descending angled surfaces at
alternating angles. Other sides of the retort 234 that couple the
first side 450 to the second side 460, not shown in the cross
section view of FIG. 4, (e.g., a front side and a back side) may be
flat.
The first and second zig-zag sides 450, 460 are aligned so that
descending angled surfaces of both sides are parallel (or
substantially parallel) producing a channel for descending shale
where the width of the channel, or the horizontal area of the
channel at different points, is constant or substantially constant.
The retort 234 is operated when filled with shale, and the shale
may be moved as a (not strictly vertical) column of solid shale
particles, rather than being gas-fluidized or liquid-fluidized.
Downward but angled motion of the shale at alternating angles
between zig-zag sides produces shear between different horizontal
planes or of the shale, preventing the shale particles from fusing
together. Angled surfaces support the descending shale, reducing
geo load at the bottom of the retort 234.
In some embodiments, angled sections of the retort 234 can be
individually assembled and transported on standard-size trucks,
then assembled at the location where the retort 234 will be
operated. Sections may include outer steel surfaces of the retort
234, which may be flange-bolted together, insulation, and
distributors 406 or collectors 408 which are described below.
Shale is conveyed to hoppers 232. In some embodiments, shale may be
mined and groomed 4 inch minus shale, with a particle size of four
inches or less. In some embodiments, hoppers 232 may be alternately
filled and emptied, so a first hopper is filled while shale is
loaded into the retort 234 from a second hopper, and vice
versa.
One or more augers 402 load shale from the hoppers 232 into a
preheat section 404 of the retort 234. Shale is loaded at the top
of the retort 234 and removed from the bottom of the retort 234
while the retort 234 is running, so the shale is loaded into the
retort 234 through one or more gas and mechanical interlocks that
prevent gases from flowing backwards out of the retort 234 to
augers 402 and hoppers 232. In some embodiments a deflector cone or
wedge is disposed at the ends of the one or more augers 402, to
direct shale particles downward into the retort 234.
Lines with arrows in FIG. 4 represent the flow of steam into the
retort 234 from the steam temperature control subsystem 236 at the
left side of FIG. 4, and the flow of steam, gases, and liquids out
of the retort 234 at the right side of FIG. 4. Superheated steam
enters the preheat section 404 of the retort 234, and is
distributed through the shale particles to preheat the shale
through preheat steam distributors, which are described below with
reference to FIG. 5.
Shale descending out of the preheat section 404 enters a first
angled section of the retort 234. The shale descends down through
subsequent angled sections of the retort 234 in zig-zag fashion. In
some embodiments, flow of the shale is laminar rather than
turbulent, so that shale particles tend to stay in zig-zag "lanes"
without a large degree of mixing across the horizontal x-y plane.
However, oblique descending motion of the shale at alternating
angles may facilitate high volume flow for faster shale processing,
consistent shear between x-y planes to avoid fusing shale particles
together, consistent transfer of heat and pyrolyzed gases/vapors
across the retort 234 (as described below), a slight tumble of
shale particles against each other to facilitate heat transfer, and
changing gas pathways across the retort 234 between moving shale
particles (resulting in even heat transfer). Heat transfer by
confection, conduction and radiation across tumbling shale
particles is facilitated by changing heat transfer pathways between
the moving shale particles.
At the bottom of the retort 234, a gas interlock prevents gases
from exiting the retort 234 with the spent (e.g., pyrolyzed) shale.
One or more grinders 416 grind the shale exiting the retort 234. A
shaker grate may be disposed above the grinders 416, in some
embodiments, to control the descent of the shale. In the depicted
embodiment, grinders 416 control the flow of shale out of the
retort 234. The speed of the grinders 416 may be controlled by a
retort operator to control the volume flow of shale through the
retort 234. In some embodiments, primary grinders 416 may be
provided to control the flow of shale, and secondary grinders (not
shown) may be provided to grind the shale more finely than the
primary grinders 416. Spent shale from the retort 234 has had oil
and gas products from kerogen pyrolyzed and removed, but includes
carbon that may be combusted at temperatures higher than pyrolysis
temperatures. The spent shale, in various embodiments, may be
transported to a shale combustion subsystem 204 as described above.
A shale combustion subsystem 204 is described in further detail
below with reference to FIGS. 9 and 10.
In the depicted embodiment, steam distributors 406 are coupled to a
first side 450 of the retort 234, and collectors 408 are coupled to
the second side 460 of the retort 234. Superheated steam is used to
heat and pyrolyze the shale, producing oil and gas products from
kerogen in the shale, which are removed from the retort 234 as
gases and vapors. The term gases may also be used herein in a
general sense to refer to gases and/or vapors. The distributors 406
and collectors 408 are coupled to the first and second sides 450,
460, respectively, to produce crossflow of steam and heat from the
first side 450 to the second side 460, across the shale particles
descending through the retort 234. Gases produced by shale
pyrolysis are entrained in the crossflow of steam, and exit the
collectors 408.
A steam temperature control subsystem 236 produces the superheated
steam. In some embodiments, if some portions of the steam
temperature control subsystem 236 are located at a distance from
the retort 234 that allows steam to cool, the steam temperature
control subsystem 236 may include one or more additional heaters
412 located nearer to the retort 234, to boost steam temperatures
for steam delivered to certain portions of the retort 234. The
steam temperature control subsystem 236 may be coupled to the steam
distributors 406, and may be configured to deliver
higher-temperature steam to an upper portion 430 of the retort 234
and lower-temperature steam to a lower portion 440 of the retort
234. In the depicted embodiment, the upper portion 430 of the
retort 234 includes the upper five angled sections, and the lower
portion 440 of the retort 234 includes the lower four angled
sections. In another embodiment, upper and lower portions 430, 440
may be divided differently.
Higher temperature steam from the steam temperature control
subsystem 236 enters the first side 450 of the retort 234 at
distributors 406 in the upper portion 430 of the retort 234. In
some embodiments, higher-temperature steam may be at or above a
shale pyrolysis temperature. For example, if pyrolysis occurs at
650.degree. F., higher temperature steam may be at a temperature of
approximately 800.degree. F.
Lower-temperature steam from the steam temperature control
subsystem 236 enters the first side 450 of the retort 234 at
distributors 406 in the lower portion 440 of the retort 234.
Lower-temperature steam may be superheated steam, above the boiling
point of water to avoid condensation in the retort 234, but may be
at a significantly lower temperature than the higher temperature
steam. For example, in one embodiment, the lower temperature steam
entering the lower portion 440 of the retort 234 may be cooled (by
mixing with water) to approximately 250.degree. F.
Steam in the preheat section 404 of the retort 234 may condense on
cold shale as it preheats the shale. In the upper portion 430 of
the retort 234, crossflow of superheated steam may drive the
condensate across the retort 234 to one or more water collectors
410. Preheating of shale and removal of condensed water avoids the
need to heat the condensed water back up to shale pyrolysis
temperatures while heating the shale. Preheating the shale and
removing the condensed water also prevents superheated steam
distributed in lower sections of the retort 234 from condensing on
the shale.
In the upper portion 430 of the retort 234, higher-temperature
steam heats the shale from the first side 450, driving a wave or
gradient of heat across the shale from the first side 450 to the
second side 460. In FIG. 4, shading within the retort 234 indicates
temperature zones, with white or no shading (e.g., at the left of
the upper portion 430 of the retort 234) indicating the highest
temperatures, large dashes (e.g., at the right of the upper portion
430 of the retort 234) indicating the lowest temperatures, and
small dashes indicating intermediate temperatures. Heat moves from
the first side 450 to the second side 460 by convection of the
steam and pyrolyzed gases, conduction between shale particles, and
radiation from hot shale particles and retort sides. As the shale
heats up, pyrolysis produces oil and gas products in gaseous form,
which exit through collectors 408.
In the lower portion 440 of the retort 234, lower-temperature steam
cools the shale. Crossflow of the lower-temperature steam continues
to drive heat across from the first side 450 of the retort 234 to
the second side 460. Thus, shale at the first side 450 of the
retort 234 is pyrolyzed in the upper portion 430, where shale at
the second side 460 of the retort 234 is not yet fully heated, and
shale at the second side 460 of the retort 234 is pyrolyzed in the
lower portion 440 as heat transfers across from the first side 450,
despite the overall cooling of the shale in the lower portion
440.
Gases and vapors at different temperatures exit different sections
of the retort 234 through collectors 408. Some vapors of heavier
oils may be driven across the retort 234 to the second side 460 and
run down the second side 460 as liquids, to be removed via one or
more oil collectors 414. Gases exiting the retort 234 via
collectors 408 may be directed through cyclonic separators 418 to
remove fine particles entrained in the exiting gases, and may then
enter a distillation subsystem 240, which is described below.
Liquids exiting the retort 234 (e.g., via one or more water
collectors 410 and/or oil collectors 414 may be heated to vaporize
the liquids and separate them from solids (e.g., fine shale
particles) suspended in the liquid, and the resulting vapor may
also enter the distillation subsystem 240. For example, the oil
collector may be couple may be coupled to higher-temperature steam
to vaporize collected oil.
Although the above description broadly describes delivery of
higher-temperature and lower-temperature steam to the retort 234,
the steam temperature control subsystem 236 may use heaters 302,
304 and/or steam/water mixers 306 to produce steam at a plurality
of different temperatures for delivery to different portions of the
retort 234. In one embodiment, the steam/water mixers 306 are
configured to produce steam above 600.degree. F. for distribution
to a preheat section 404 of the retort 234. In some embodiments,
steam/water mixers 306 are configured to produce steam at or above
625.degree. F., at or above 650.degree. F., or at or above
675.degree. F. for distribution to a preheat section 404 of the
retort 234.
In one embodiment, the steam/water mixers 306 are configured to
produce steam above 750.degree. F. for distribution to an upper
portion 430 of the retort 234. In some embodiments, steam/water
mixers 306 are configured to produce steam at or above 800.degree.
F., at or above 850.degree. F., at or above 900.degree. F., or at
or above 950.degree. F. for distribution to an upper portion 430 of
the retort 234.
In one embodiment, the steam/water mixers 306 are configured to
produce steam below 300.degree. F. for distribution to a lower
portion 440 of the retort 234. In some embodiments, steam/water
mixers 306 are configured to produce steam at or below 275.degree.
F., at or above 250.degree. F., or at or below 225.degree. F. for
distribution to a lower portion 440 of the retort 234.
Although the use of steam is described herein for heating and
pyrolyzing shale, hot gases other than steam may be used in some
embodiments to similarly heat and pyrolyze shale. In further
embodiments, the structures described herein as steam distributors
406 and collectors 408 may be used as hot gas distributors and
collectors.
FIG. 5 is a perspective view illustrating one embodiment of a
preheat section 404 for a retort 234. As in FIG. 4, certain
exterior components have been omitted to depict components in the
interior of the retort 234. As described above, the preheat section
404 in the depicted embodiment receives and preheats shale entering
the top of the retort 234. In the depicted embodiment, augers 402
move shale from hoppers 232 into the retort 234, and a deflector
cone 502 at the ends of the augers 402 directs direct shale
particles downward into the retort 234. Unlike in other sections of
the retort 234, where steam distributors 406 are coupled to the
first side 450, the preheat steam distributors 506 in the preheat
section 404 are disposed between the first side 450 and the second
side 460 to distribute steam more uniformly within the shale bed.
This more uniform distribution of steam may increase the
temperature of the shale above the boiling point of water across
the preheat section 404, thus avoiding cold spots where superheated
steam added lower in the retort 234 might condense.
In the depicted embodiment, the preheat steam distributors 506 are
hollow vertical rods with side ports. These hollow vertical rods
506 extend downward from a grate 504 with hollow members for
receiving steam and distributing steam to the hollow vertical rods
506. Thus, steam provided to the preheat section 404 enters the
grate 504 and the hollow vertical rods 506, and exits the rods 506
into the shale bed via the side ports in the rods 506. The use of a
grate 504 and hollow vertical rods 506 to distribute steam allows
the shale to travel vertically through the preheat section 404,
while steam is distributed to preheat shale across the retort 234
rather than only at the first side 450. However, in various other
embodiments, preheat steam distributors 506 of various other or
further shapes may be used to preheat shale entering the top of the
retort 234.
FIG. 6 depicts the retort 234 in a perspective view, looking down
into the retort 234 from below the preheat section 404. Individual
angled sections 602 of the retort 234 may be transported
separately, and bolted together at flanges 604. Additionally, some
components that were omitted for clarity in FIG. 4, such as front
and back walls, are depicted in FIG. 6. Ribs on the flat front and
back sides of the retort 234 prevent steam and pyrolysis gases from
skirting around the perimeter of the shale bed.
FIG. 7 depicts a steam distributor 406 and a collector 408 for a
retort 234, in one embodiment. Arrows illustrate the flow of steam
from the distributor 406 to the collector 408, across the retort
234. In some embodiments, distributors 406 and collectors 408 are
made of steel, which is treated as sacrificial. Sacrificial
distributors 406 and collectors 408 may be replaced when the retort
234 is serviced. A distributor 406 or a collector 408 includes a
first side with a large hole, a second side with small slots or
holes, and an air gap between the first and second sides. In one
embodiment, the sides may be two inches thick, and the air gap may
be six inches thick. For distributors 406, steam enters from the
steam temperature control subsystem 236 through the large hole,
passes through the air gaps and exits the distributor 406 to heat
shale particles in the retort 234 through the small slots. For
collectors 408, steam and other gases exit the shale and enter the
collector 408 through the small holes, cross the air gap, and are
removed from the retort 234 through the large hole. In some
embodiments, collectors 408 may include a filter medium such as
coiled steel in the air gap, to remove particles from the exiting
gases.
In some embodiments, distributors 406 and/or collectors 408 in
various sections of the retort 234 may be separated from outer
walls of the retort 234 by insulation. Outer walls of may be bolted
or otherwise fastened together, and may be air-cooled. Due to air
cooling and insulation, outer walls may be at a lower temperature
than distributors 406 and/or collectors 408, and may therefore
expand less than distributors 406 and/or collectors 408.
Accordingly, distributors 406 and/or collectors 408 may be shorter
or smaller than outer walls of corresponding sections of the retort
234, so that expansion of the distributors 406 and/or collectors
408 does not push the sections of the retort 234 apart.
FIG. 8 is a diagram illustrating one embodiment of a distillation
subsystem 240, as described above. In some embodiments, a
distillation subsystem 240 includes a plurality of liquid/gas
separation vessels 804a-e that receive gases from the retort 234,
and a plurality of organic Rankine cycle (ORC) generators 806
corresponding to the separation vessels 804a-e. As in other
diagrams herein, lines or pipes indicate connections or gas flow
between components without indicating exact spatial relationships.
Additionally, in various embodiments, a distillation subsystem 240
may include more or fewer separation vessels 804a-e and ORC
generators 806. For example, FIG. 1 depicts a much larger number of
ORC generators 806 in the distillation subsystem 240.
Gases (and liquids) exiting the retort 234 enter the distillation
subsystem 240 at the left side of FIG. 8, having been filtered at
cyclonic separators 418 to remove fine particles entrained in the
exiting gases. As described above, gas fractions at different
temperatures exit different sections of the retort 234, and are
received by the distillation subsystem 240. Lighter hydrocarbons
exit the retort 234 as shale particles are pyrolyzed, and may be
found in gas fractions from multiple sections of the retort 234.
Medium-weight to heavy hydrocarbons may be produced by pyrolysis at
a pyrolysis temperature that is lower than the boiling point for
those oils, and may condense on shale particles in the retort 234
as liquid. As the heat waves are driven across the retort 234 and
the shale particles descend, medium-weight to heavy hydrocarbons
may be volatilized lower in the retort 234 so that medium to heavy
hydrocarbons exit the retort 234 in gas fractions from medium to
low sections of the retort 234, and heavy hydrocarbons exit the
retort 234 lower still. Thus, in general, gas fractions from the
top of the retort 234 may include light hydrocarbons, gas fractions
from the middle of the retort 234 may include light and medium
hydrocarbons, and gas fractions from the bottom of the retort 234
may include light, medium, and heavy hydrocarbons.
The distillation subsystem 240 includes a plurality of liquid/gas
separation vessels 804a-e, and a plurality of ORC generators 806
(or other heat-powered electrical generators) corresponding to the
separation vessels 804a-e. The separation vessels 804a-e include
heat exchangers through which the working fluid of the ORC
generators 806 circulates, to transfer heat from the gas fractions
to the working fluid. This heat transfer results in condensation of
distillate products, which may be removed from the separation
vessels 804a-e as liquids. The ORC generators 806 are coupled to
and powered by heat exchangers of the separation vessels 804a-e. In
some embodiments, ORC generators 806 may be TURBODEN.RTM.
generators or other electrical generators powered by heating a
working fluid. The ORC generators 806 produce electricity 100, and
may be cooled by cooling water, which in turn may be circulated to
ponds 220 where algae may use low grade waste heat. Flow of cooling
water is indicated by arrows into and out of the ORC generators 806
at the right of FIG. 8. Cooling water may be provided to ORC
generators from a common source, or may be provided to groups of
ORC generators chained together so that the cooling water is
gradually heated by multiple generators before being circulated to
algae ponds 220.
The ORC generators 806 include a plurality of different working
fluids (for different generators 806) which circulate through heat
exchangers of corresponding separation vessels 804a-e in
self-contained loops, thus producing different condensation
temperatures for gases in different separation vessels 804a-e. In
some embodiments, the combination of multiple liquid/gas separation
vessels 804a-e with different condensation temperatures may
function similarly to a distillation column to produce heavier and
lighter oil fractions, which are removed from the liquid outputs of
the liquid/gas separation vessels 804a-e, and stored in liquid
storage tanks 252.
In the depicted embodiment, the separation vessels 804a-e include
four separation vessels 804a-d for condensing hydrocarbons at
different condensation temperatures, and a fifth separation vessel
804e for condensing water. In another embodiment, a system 100 may
include more or fewer separation vessels. For example, to produce
more or fewer than four different distillate fractions at different
condensation temperatures, more or fewer than four separation
vessels for condensing hydrocarbons may be provided.
In the depicted embodiment, the liquid/gas separation vessels
804a-e are coupled in a chain, so that gases exiting earlier
separation vessels in the chain are received by later separation
vessels in the chain. For example, the gas output of separation
vessel 804a is coupled as an input to separation vessel 804b, the
gas output of separation vessel 804b is coupled as an input to
separation vessel 804c, the gas output of separation vessel 804c is
coupled as an input to separation vessel 804d, and the gas output
of separation vessel 804d is coupled as an input to separation
vessel 804e. Chaining together of separation vessels 804a-e allows
lighter hydrocarbons that are not condensed with the heavier oil
fractions to transfer to subsequent separation vessels to be
potentially condensed with lighter oil fractions. In the depicted
embodiment, the gas output of separation vessel 804d includes gases
that were not condensed in the separation vessels 804a-d, and
removed as oil fractions. The non-condensed gases received by
separation vessel 804e may include lighter hydrocarbons
C.sub.1-C.sub.6, hydrogen, carbon dioxide, hydrogen sulfide, steam
and/or water vapor.
In the depicted embodiment, two-stage distillation is performed at
separation vessel 804e to condense water, which is removed from the
vessel 804e as a liquid and stored in hot feedwater tanks 212. In
some embodiments, a separation vessel may include two heat
exchangers. In the depicted embodiment, two heat exchangers per
separation vessel 804a-e are indicated as wavy lines inside the
outline of the separation vessels 804a-e. One of the heat
exchangers (to the right in FIG. 8) for a separation vessel 804a-e
is coupled to the corresponding ORC generator 806, so that the
working fluid for the ORC generator 806 circulates through that
heat exchanger, and the boiling point of that fluid determines the
temperature at which hydrocarbons condense within the separation
vessel 804a-e.
In some embodiments, water distilled in separation vessel 804e may
be circulated through second heat exchangers (to the left in FIG.
8) of the other separation vessels 804a-d, adding a portion of the
latent heat of vaporization back to the water, thus allowing the
water to be more rapidly boiled to produce steam in the shale
combustion subsystem 204. Heat exchangers used to heat water at the
separation vessels 804a-d may be chained together so that water
passes through and is heated by a series of the separation vessels
804a-d prior to being stored in the feedwater tanks 212.
Water from the feedwater tanks 212 may be used to produce
superheated steam in the shale combustion subsystem 204, as
described below, or may be used by steam/water mixers 306 to
control the temperature of superheated steam entering different
sections of the retort 234, as described above. With the water
removed at separation vessel 804e, other non-condensed gases, which
may include lighter hydrocarbons C.sub.1-C.sub.6, hydrogen, carbon
dioxide, and/or hydrogen sulfide are removed from the gas output of
separation vessel 804e. These gases may be processed by a gas plant
to separate, purify, or otherwise treat or use the gases, and
stored in gas storage tanks 254.
FIG. 9 is a diagram illustrating one embodiment of a shale
combustion subsystem 204, in a side view. As described above, a
shale combustion subsystem 204 combusts pyrolyzed shale from the
retort 234, and uses heat from the combustion to boil water and
superheat the resulting steam. In the depicted embodiment, the
shale combustion subsystem 204 includes an upper hopper 904, a
combustion chamber 906, a blower 908, a duct 910, a heat exchanger
912, a boiler 914, a cyclonic separator 916, and a lower hopper
918. Superheated steam exits the shale combustion subsystem 204 to
the steam temperature control subsystem 236 via steam pipe 902,
while gasses from combustion exit the boiler 914 to the filter
house 218. Although the side view of FIG. 9 shows one combustion
chamber 906, one heat exchanges 912, one boiler 914, and so on,
some embodiments of a system 100 may include multiple combustion
chambers 906, heat exchangers 912, boilers 914, and so on.
In the depicted embodiment, pyrolyzed shale received from the
retort 234 is combusted in one or more combustion chambers 906, and
heat from the combustion of the pyrolyzed shale is used in one or
more heat exchangers 912 for superheating steam for the steam
temperature control subsystem 236. In the depicted embodiment, the
steam is produced in one or more boilers 914. In general, in
various embodiments, of a shale combustion subsystem 204,
combusting or combusted shale and combustion gases may flow in one
direction opposite to a counterflow of water and/or steam, to
transfer heat from combustion into the water and/or steam.
Shale is conveyed to the upper hopper 904, and moved by augers into
the combustion chamber 906. The shale is combusted in the
combustion chamber 906, in a flow of air provided by blower 908. In
some embodiments, shale may be gas-fluidized by the air from the
blower 908, resulting in efficient combustion due to a high surface
area for contact between air and finely ground shale. Shale
continues to combust as it descends through heat exchanger 912. The
heat exchanger 912 is jacketed so that steam flows up along the
outside, so that descending and combusting shale and gases in the
center of the heat exchanger 912 heats the ascending steam in the
jacket. Combustion gases also move down through the heat exchanger
912 due to expansion of the gases in combustion, the pressure
maintained by the blower 908, and pressure from the weight of
falling shale particles. One or more cyclonic separators 916 are
disposed between the heat exchanger(s) 912 and the boiler(s) 914,
for removing solid combusted shale particles from the hot
combustion gases. In some embodiments, the cyclonic separators 916
include one or more heat exchangers inside the cyclonic separators
916 and/or as a jacket to further transfer heat from the shale and
gases to the steam. The combusted shale descends into the lower
hopper 918, and may be removed by a conveyor 208. The duct 910 may
feed air to the blower 908, and may first direct the air past the
shale in the lower hopper 918, to preheat the blower air.
The boiler(s) 914 are configured to heat pressurized water and
produce steam at one or more pressure release valves (not shown).
Water may be heated under pressure to above the (atmospheric
pressure) boiling point, so that it converts to steam at the
pressure release valves. Expansion as the water turns to steam or
is subsequently heated may drive the steam through the rest of the
system 100, including through jackets in the heat exchanger(s) 912
and cyclonic separators 916 where it receives heat from combustion.
A pump 210 may provide pressurized water from the feedwater tanks
212 to the boiler(s) 914. Water may be received in the feedwater
tanks 212 from the distillation subsystem 240 at or near the
boiling point, and the feedwater tanks 212 may be insulated. In
some embodiments, water may be held in the feedwater tanks 212 at
the boiling point and with additional latent heat added, but not
enough heat to boil the water. Supplying such heated water to the
boilers 914 may allow efficient boiling to produce steam. Exhaust
gas from combustion exits the boiler(s) 914 and is received by
filter house(s) 218, which are described below.
FIG. 10 is a perspective view illustrating embodiments of certain
components of a shale combustion subsystem 204, as described above.
The boiler 914 is depicted without its outer casing, and a section
is not depicted between a combustion chamber 906 and a heat
exchanger 912, to better illustrate internal components of the
shale combustion subsystem 204. In the depicted embodiment, the
heat exchangers 912 for superheating steam include vertical
compartments for ascending steam to be heated by descending shale
particles and combustion gases. In the depicted embodiment, the
vertical compartments for ascending steam surround an inner
compartment for descending shale particles and combustion gases. In
the depicted embodiment, the boilers 914 include horizontal
compartments for water (traveling right to left in FIG. 10) to be
heated by gases (traveling left to right in FIG. 10) from which
solids have been removed (e.g., by cyclonic separators 916).
FIG. 11 is a perspective view illustrating one embodiment of a
filter house 218, as described above. Outer walls of the filter
house 218 are not depicted, so as to better display internal
components. In various embodiments, a filter house 218 may include
a plurality of iron-zinc filters 1102. Combustion gases flow
horizontally through holes in the filters 1102, and a vertical flow
of water is provided (e.g., over the surface of the filters 1102,
as drops descending between filters 1102, or the like). The
iron-zinc filters 1102 remove hydrogen sulfide from a horizontal
flow of combustion gases. The vertical flow of water cools the
gases and removes carbon dioxide, so the carbon dioxide from the
carbon gases becomes dissolved in the water. The resulting carbon
enriched water may be provided to one or more algae ponds 220 for
production of algae oil.
The present invention may be embodied in other specific forms
without departing from its spirit or essential characteristics. The
described embodiments are to be considered in all respects only as
illustrative and not restrictive. The scope of the invention is,
therefore, indicated by the appended claims rather than by the
foregoing description. All changes which come within the meaning
and range of equivalency of the claims are to be embraced within
their scope.
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